My parents suspected when I was about four.

I would arrange correctly the vivid primary coloured blocks of my toys (banging coloured shapes into appropriate dimensioned holes with a rubber hammer was apparently a favourite)
but anything less than the vivid primary colours I was liable to confuse. By the time I was able to start naming things it was increasingly obvious; be it crayons, clothes or food, I was repeatedly misidentifying what colour they were.

A memorable trip to The Natural History Museum in London was another turning point. In the exhibit on The Human Body¹ there is an exhibit on the eye and it includes a display on colour vision and colourblindness. One can review slides of the standard diagnostic test for colourblindness Shinobu Ishihara's 36 plates of coloured dots with the numbers cunningly disguised to befuddle anyone with altered colour sensitivity. My infant self betrayed my inadequacies by performing all the classic misreading of the Ishirara test.

By the time the formal colour vision tests rolled around at school (Ishihara again) it was pretty much a foregone conclusion.

Well aside from being told the story above, it was for me, being simply unable to colour things in correctly or recognise colours

Not that it mattered to me much, but other people would notice on my behalf.

For years, my anti-smoking posters at school had cigarette butts in brightest green.
My Union Jack was easy to identify. It was purple and orange.
Mum had kindly labelled all of my pens, the other children found this a hysterical source of amusement and torture.

I've always been a keen drawer of cartoons, When I first got a computer I'd spend ages doodling on the paint programmes. It was something of a despondent moment to discover my deserts were shade of green only slightly dissimilar from my forests.

All my drawings throughout my youth were in my own special palette of the colours only I could see.

And it continues.

There was a lot of hoo-ha in the news recently about a beloved British brand Cadbury Chocolates being taken over by US Multinational Kraft, “the famous purple wrapper” the newsman announced.

Purple? I’m 29. I had no idea. I thought they were blue!

Well disability, let’s just define that, depends on how society is organised. Everyone has their own unique set of colour-sensitive cells and people all vary so colour vision varies.
What I have is an altered sensitivity to the spectrum of visible light. My visible spectrum is essentially shortened with less distinction between coloured groups. I have a drastically fewer set of hues I can recognise. This only matters when things are categorised by colour then I am adrift in a canoe without a paddle.

Otherwise I get on quite nicely thank you very much and it tends to just be in the background. I only find myself noticing it when I encounter that moment's puzzlement if I can't quite place what colour something is supposed to be or follow a direction or know that something I'm seeing just cannot be right.²
A recent example, only a trivial one. I was attending a job interview for a job with the council and in the waiting area was a calendar which denoted all the religious festivals of about 10 different faiths. Being an atheist, I was amused to see it was ecumenical enough to include Jainism and Zoroastrians.

The key was colour coded and the days and months were festooned with little coloured dots, which were meant to be wonderfully informative about which festivals from which religions fell on which dates. It swiftly dawned this wasn't working for me.

There were purples and blues, oranges and browns, yellow and greens - I found myself looking back and forth between the calendar and the key and just being unable to follow which was which. It's rarely the case that I cannot see the colour, I just cannot tell different colours apart. Sometimes different festivals of indistinguishable colours fell on the same day which begat another round of darting back and forth to the key. Very small areas of colour are worse than large areas I find. I think that has to do with how much of the reflected light is falling on my retina. But it's a prime example of what I mean about suddenly being adrift when it is simply expected that you can see different colours and recognise them.

All these thoughts were internal, of course, but if someone had been there and said "what about that one, what colour is that?" I’d have been guessing. Now that's something I'm rather proud to say I’ve gotten pretty good at: guessing. but it involves using other kinds of clues such as how bright different colours are, the context they are in. Start to take those away (like with tiny abstract dots) and I'll get lost very easily. Also false positives are self correcting you guess green right once, well that must mean the other one is yellow and other similar deductions.

I’m a diagnosed protanope. This means I am very strong red-blind, and this cuts a swathe through my sensitivity to reds, greens, browns, yellow, oranges, and the pseudoisochromatic colours³ with which I can (and do) confuse them.

Thus, red can appear black or dark grey, but not always. It depends on lighting, context, and brightness. My own blood for instance to me looks brown, in fact it took some persuasion to convince me that it should be red. I do see a red – coca cola cans for example, but I’d bet what I think of as red probably isn’t and is very much dependent on the context. If you could extract my coca-cola red and put it say on snooker balls, I'd still try potting the green before the brown and ceding points to the opponent because in spite of the science of it colour is highly contextual and my red is red for me but isn't really red. It's that colour than is also like brown or green or black, sometimes. That’s why grass is green. Of course grass is green. But green in other contexts is where hue, and brightness combine to confound me. And I'll still lose orange Frisbees in the green grass.

The colours I struggle with most often are:

• Red and black - contrast matters here. I've handed in essays in red type before because of a highlighting error but red on high contrast white is to me like black. I cannot distinguish them.


• Blue and purple, (See Cadbury's Wrappers)


• Orange and certain browns like tans.


• Green and Yellow (the brighter the green the more likely I'll mistake it for yellow)


• Grey, certain (blue) greens and pink I know are completely interchangeable, and many is the time I've run through the list before alighting on the correct one.


• Everyone all thinks traffic lights should be hard, they aren’t – not really. I learnt them by sequence. I'll even call the top one "red", the bottom one "green" even though to me they are nothing of the sort. The two red and amber, to me look like slightly different species of yellow (the "red" is ever so slightly darker) And the "green" at the bottom, is I think white – it doesn't look much different than an ordinary light bulb.


Of slightly more difficulty are brake-lights. Recognising those from tail lights is hard.

I’ve hit the brakes hard, once to often now to believe that It's not just poor driving technique.

I have very sympathetic parents. My brother is the same way, so they coped with both of us down the years. But I'm the eldest so was the guinea pig for most of this. Famously my brother got quite irate with the doctor administering the colour tests as he was very proud of being able to count and deeply frustrated to find out the "number book: he was given had no numbers in it. Mum recalls the moment in the Ishihara test when the plates switch to numbers colourblind people can see but people with normal vision cannot. My infant brother began reeling of numbers to the clear astonishment of my parents and the doctor who could only see what is commonplace for us: as meaningless assemblage of dots and spots. That's when mum says she understood. We don't live in the same world.

Teachers, I think don’t get it. And I don’t blame them. Colours are a second alphabet. People assume you know what they are talking about. Even when you tell them, if they remember at all, it’s rare that they alter their behaviour.

And what do you tell them?
I’m colour blind.

What you can’t see colours?

Well..yes..or …no..it's...um...I..can’t tell them apart.

What colours’ this [ ]⁴ then?

And that’s how it usually goes.

"Colour vision deficiency" takes longer to say, as does the explanation of why colourblindness is really inaccurate. I prefer CVD but I don’t think it really helps people understand. I’d prefer they had a solid grounding in colour-theory instead.

It’s taken some time for me to get my head round it, but I've found trying to understand it has helped me come to terms with it. I am not sensitive (cannot see) certain hues. The colours I can see are modulated by brightness. That's more often than not how I tell them apart but lighting affect brightness becuase brightness is the amount of reflected light. A second factor is saturation, how much of a hue is mixed with white to desaturate a colour. Desaturated colours are very hard to distinguish if you cannot tell the hues apart. A sufficiently desaturated bright green I'm liable to think is pink just as a sufficiently bright green is as yellow to me. At root of all of this is the mechanics of light. Those purple Cadbury wrappers are an interesting demonstration of this. With purple what is absorbed are all the wavelengths of white light that aren't blue or red and these are reflected. My eyes cannot detect the red light but I can detect the blue. The more red a purple contains so it follows the less blue light is reflected. Brightness is the degree to which light is reflected so hence all purples appear as species of lighter or darker blues according to the proportion of red that I am 'blind' to

My solutions are if it’s important that it’s coloured I label it. That hasn't changed since the colour pens of school. It is simply no good relying on me to see a colour and recognise it. I need that second level of information like a name written down.

Second, I ask people. I’m pretty up front about saying I’m colour blind: I can’t see that. What colour is it? That usually works, with the above caveat that I'm pretty sure no-one has any idea what I’m actually talking about.

I know people with conditions similar to my own find buying fresh fruit labourious because it's hard to know which banana is ripe. In my own life it was pointed out to me, that I shop for clothes by texture, I’ll go around scrunch up shirt sleeves and jumpers to see how they feel. The texture is more important to me than the colour. My wardrobe also reflects a certain bias. Lots of blues (which I can see); lots of dark colours, greys, a few greens (definitely green not pink) and black.

Probably the best thing is just some simple advice to let your child discover what colours they can and can't see, not to encourage a stigmatisation but to help them to see the world in a way they can manage.

An introduction to Ishihara would I think be good as that is what they will likely encounter and have to sit with their child through, what it means and how it diagnoses.

Given how few people I think truly understand colour and colour vision deficiencies like mine, that I would personally want an easy to understand overview of what colour is (wavelengths of reflected light), the idea of a colour gamut, a colour space, (RGB etc)

And then how colourblindness changes that. How the axes of the pseudoisochromatic colours that exist in those spaces for people like me are determined. How the Ishihara test uses this to diagnose which spectral colours of light you are not sensitive to. Also how brightness and saturation matter.

The other thing I think I'd add is a brief gloss on what colourblindness is and what it is not. It does not mean that my world is uncoloured. I swear to you it isn’t. I just have no idea what those colours are called.

It’s rather like having a virtuoso chef who with a little ingenuity can create all the worlds dishes out of only three ingredients. A little of this, a little of that, a pinch of the other. and foompf egg salad nicoise Shazzam fillet steak.

Then try imagining taking away one his ingredients. Yes, with the same ingenuity and skill he can still make all those different foods in all the variety, but without that extra thing, everything he makes is just the little bit more bland and 'samey'. Soups feels a lot like custard. You realise some dishes you can't really tell them apart anymore.

This would be flavour blindness.

I’m colourblind in the same way.

¹It's still there. Turn left by the Diplodocus in Reception, and it's on the right, just past the entrance to dinosaurs.²I've lost count of the number of times I had to convince myself, that that the gloopy orange Cream of Tomato soup I just purchased from Tescos, simmering away in the pan isn't in fact green. Eventually I find myself repeating a mantra. "It's tomato soup. Tomato soup isn't green. It's just you."³A technical term, if you'll forgive me - it means colours which look the same but aren't really. For a slightly complicated reason it's possible to calculate which are the the pseudoisochromatic colours for the absence or weakness in sensitivity to one or more of the spectral colours (red, green or blue) which results in colourblindness; The Ishiara test plates are painted in these shades, which is why they can diagnose those who can see the numbers and those who cannot.⁴[] insert nearest object here.